A Mini-Review on Chitosan-Based Hydrogels with Potential for Sustainable Agricultural Applications

Recent advances in synergistic use of GQD-based hydrogels for bioimaging and drug delivery in cancer treatment

Graphene quantum dot (GQD) integration into hydrogel matrices has become a viable approach for improving drug delivery and bioimaging in cancer treatment in recent years. Due to their distinct physicochemical characteristics, graphene quantum dots (GQDs) have attracted interest as adaptable nanomaterials for use in biomedicine. When incorporated into hydrogel frameworks, these nanomaterials exhibit enhanced stability, biocompatibility, and responsiveness to external stimuli. The synergistic pairing of hydrogels with GQDs has created new opportunities to tackle the problems related to drug delivery and bioimaging in cancer treatment. Bioimaging plays a pivotal role in the early detection and monitoring of cancer. GQD-based hydrogels, with their excellent photoluminescence properties, offer a superior platform for high-resolution imaging. The tunable fluorescence characteristics of GQDs enable real-time visualization of biological processes, facilitating the precise diagnosis and monitoring of cancer progression. Moreover, the drug delivery landscape has been significantly transformed by GQD-based hydrogels. Because hydrogels are porous, therapeutic compounds may be placed into them and released in a controlled environment. The large surface area and distinct interactions of graphene quantum dots (GQDs) with medicinal molecules boost loading capacity and release dynamics, ultimately improving therapeutic efficacy. Moreover, GQD-based hydrogels' stimulus-responsiveness allows for on-demand medication release, which minimizes adverse effects and improves therapeutic outcomes. The ability of GQD-based hydrogels to specifically target certain cancer cells makes them notable. Functionalizing GQDs with targeting ligands minimizes off-target effects and delivers therapeutic payloads to cancer cells selectively. Combined with imaging capabilities, this tailored drug delivery creates a theranostic platform for customized cancer treatment. In this study, the most recent advancements in the synergistic use of GQD-based hydrogels are reviewed, with particular attention to the potential revolution these materials might bring to the area of cancer theranostics.

Nanocellulose/wood ash-reinforced starch-chitosan hydrogel composites for soil conditioning and their impact on pea plant growth

Hydrogels are 3-dimensional polymer networks capable of absorbing a large amount of water. Natural polymeric hydrogels are biodegradable, non-toxic and biocompatible. They can effectively retain nutrients for the plant and can be used as soil conditioners. This study uses a chemical cross-linking technique to synthesize starch and chitosan-based hydrogel using citric acid as a cross-linker. Additionally, hydrogel composites were developed by incorporating wood ash, nano-cellulose, and NPK (nitrogen-phosphorus-potassium) fertilizer as fillers to enhance their properties. The formulated hydrogel/hydrogel composite samples were characterized by FTIR spectroscopy, SEM analysis, X-ray diffraction and thermo-gravimetric analysis. The experiment results showed the chemical cross-linking among the polymeric chain and the semi-crystalline nature of the hydrogel/hydrogel composite samples. The swelling capacity of the hydrogel/hydrogel composite samples was 200-420% (in distilled water) and 104-220% (in saline medium) and demonstrated biodegradability within 110 days. The NPK reinforced hydrogel composite showed an excellent effect on the growth of pea plants (leaves count = 37, stem height = 20.2 cm), and could be effectively used as soil conditioners for agricultural applications. Considering the ability of hydrogel composites to reduce irrigation needs, enhance nutrient retention, and improve crop production, these novel hydrogel composites present an economically viable solution for sustainable agricultural practices.

Nanocellulose: Structure, modification, biodegradation and applications in agriculture as slow/controlled release fertilizer, superabsorbent, and crop protection: A review

This review investigates the potential of nanocellulose in agriculture, encompassing its structure, synthesis, modification, and applications. Our investigation of the characteristics of nanocellulose includes a comprehensive classification of its structure. Various mechanical, chemical and enzymatic synthesis techniques are evaluated, each offering distinct possibilities. The central role of surface functionalization is thoroughly examined. In particular, we are evaluating the conventional production of nanocellulose, thus contributing to the novelty. This review is a pioneering effort to comprehensively explore the use of nanocellulose in slow and controlled release fertilizers, revolutionizing nutrient management and improving crop productivity with reduced environmental impact. Additionally, our work uniquely integrates diverse applications of nanocellulose in agriculture, ranging from slow-release fertilizers, superabsorbent cellulose hydrogels for drought stress mitigation, and long-lasting crop protection via nanocellulose-based seed coatings. The study ends by identifying challenges and unexplored opportunities in the use of nanocellulose in agriculture. This review makes an innovative contribution by being the first comprehensive study to examine the multiple applications of nanocellulose in agriculture, including slow-release and controlled-release fertilizers.

A review on versatile applications of biomaterial/polycationic chitosan: An insight into the structure-property relationship

Chitosan is a versatile and generous biopolymer obtained by alkaline deacetylation of naturally occurring chitin, the second most abundant biopolymer after cellulose. The excellent physicochemical properties of polycationic chitosan are attributed to the presence of varied functional groups such as amino, hydroxyl, and acetamido groups enabling researchers to tailor the structure and properties of chitosan by different methods such as crosslinking, grafting, copolymerization, composites, and molecular imprinting techniques. The prepared derivatives have diverse applications in the food industry, water treatment, cosmetics, pharmaceuticals, agriculture, textiles, and biomedical applications. In this review, numerous applications of chitosan and its derivatives in various fields have been discussed in detail with an insight into their structure-property relationship. This review article concludes and explains the chitosan's biocompatibility and efficiency that has been done so far with future usage and applications as well. Moreover, the possible mechanism of chitosan's activity towards several emerging fields such as energy storage, biodegradable packaging, photocatalysis, biorefinery, and environmental bioremediation are also discussed. Overall, this comprehensive review discusses the science and complete information behind chitosan's wonder function to improve our understanding which is much needful as well as will pave the way towards a sustainable future.

Superabsorbent hydrogels based on natural polysaccharides: Classification, synthesis, physicochemical properties, and agronomic efficacy under abiotic stress conditions: A review

Superabsorbent polymers (SAPs) are a class of polymers that have attracted tremendous interest due to their multifunctional properties and wide range of applications. The importance of this class of polymers is highlighted by the large number of publications, including articles and patents, dealing with the use of SAPs for various applications. Within this framework, this review provides an overview of SAPs and highlights various key aspects, such as their history, classification, and preparation methods, including those related to chemically or physically cross-linked networks, as well as key factors affecting their performance in terms of water absorption and storage. This review also examines the potential use of polysaccharides-based SAPs in agriculture as soil conditioners or slow-release fertilizers. The basic aspects of SAPs, and methods of chemical modification of polysaccharides are presented and guidelines for the preparation of hydrogels are given. The water retention and swelling mechanisms are discussed in light of some mathematical empirical models. The nutrient slow-release kinetics of nutrient-rich SAPs are also examined on the basic of commonly used mathematical models. Some examples illustrating the advantages of using SAPs in agriculture as soil conditioners and agrochemical carriers to improve crop growth and productivity are presented and discussed. This review also attempts to provide an overview of the role of SAPs in mitigating the adverse effects of various abiotic stresses, such as heavy metals, salinity, and drought, and outlines future trends and prospects.

Ocular antibacterial chitosan-maleic acid hydrogels: In vitro and in vivo studies for a promising approach with enhanced mucoadhesion

The aim was to design and evaluate a chitosan-based conjugate providing high mucoadhesiveness and antibacterial activity for ocular infections treatment. Chitosan was conjugated with maleic acid via amide bond formation and infrared spectroscopy. Furthermore, 2,4,6-Trinitrobenzene sulfonic acid (TNBS) allowed characterization and quantification of conjugated groups, respectively. Biocompatibility was tested via hemolysis assay and Hen's Egg-Chorioallantoic membrane test. Characterization of the pH and osmolarity of hydrogels was followed by mucoadhesion assessment utilizing rheology. In addition, antibacterial studies were carried out towards Escherichia coli by broth microdilution test and agar-disk diffusion assay. In vivo studies were carried out following the already established Draize test and determining pharmacokinetic profile of dexamethasone in aqueous humour. The conjugate exhibited a degree of modification of 50.05 % and no toxicity or irritability. Moreover, mucoadhesive properties were enhanced in 2.68-fold and 1.81-fold for elastic and viscous modulus, respectively. Furthermore, rheological synergism revealed the presence of a gel-like structure. Additionally, broth microdilution and agar disk diffusion studies exhibited enhancement in antibacterial activity. Finally, in vivo studies manifested that hydrogels were highly tolerated, evidencing promising characteristics of the developed conjugate. The conjugate presented promising antimicrobial, long lasting mucoadhesive features and highly improved pharmacokinetics, leading to a revolutionizing approach in the treatment of ocular bacterial infections.

Improved Soil Amendment by Integrating Metal Complexes and Biodegradable Complexing Agents in Superabsorbents

The superabsorbents' application as materials for the preparation of modern mineral fertilizers of controlled activity is presented. Under the static conditions, the commercial acrylic-based Agro® Hydrogel was used as a sorbent for Cu(II), Fe(III), Mn(II), and Zn(II) ions in the presence of three biodegradable complexing agents of the new generation: (N-1,2-dicarboxyethyl)-D,L-aspartate acid (IDHA), N,N-ethylenediaminedisuccinic acid (EDDS) and N,N-bis(carboxymethyl) glutamic acid (GLDA). The ions and complexes concentrations were determined by the inductively coupled plasma optical emission spectrometer (ICP-OES). The characterization of hydrogel before and after the adsorption process was made using the Fourier transform infrared spectroscopy (FT-IR), surface area determination (ASAP), scanning electron microscopy (SEM-EDS) as well as the thermogravimetric (TGA) methods. The influence of the phase contact time, initial concentration, and pH on the adsorption capacities was investigated. The kinetic and adsorption parameters were determined. The Langmuir, Freundlich, Dubinin-Radushkevich, and Temkin adsorption models were applied to describe the experimental data. The Langmuir isotherm model accurately characterized the equilibrium process. The adsorption process was fast, and it reached equilibrium after 60 min of the phase contact time. The research on the adsorption of Cu(II), Fe(III), Mn(II), and Zn(II) onto Agro® Hydrogel with IDHA, EDDS, and GLDA indicates that these complexing agents improve process efficiency.

Green Hydrogels Loaded with Extracts from Solanaceae for the Controlled Disinfection of Agricultural Soils

The UN 2030 Agenda for Sustainable Development established the goal of cutting the use of pesticides in the EU by 50% by 2030. However, a ban on pesticides could seriously affect the productivity of agriculture, resulting in severe issues due to global hunger and food deficiency. Controlled release (CR) of bioactive chemicals could play a valid alternative in this context. To this aim, two biodegradable polymers, namely sodium alginate (AL) and sodium carboxymethylcellulose (CMC), were employed to obtain crosslinked hydrogel beads for the encapsulation and CR of glycoalkaloids extracted from tomato and potato leaves to be used as biocompatible disinfectants for agricultural soils. The physico-chemical characterization of the controlled-release systems was carried out by means of Attenuated Total Reflectance-Fourier Transform Infrared (ATR-FTIR) spectroscopy, Scanning Electron Microscopy (SEM), thermogravimetry (TGA), differential scanning calorimetry (DSC) (FWI > 80%) and drying kinetics. The plant extracts and the encapsulation efficiency (~84%) were, respectively, characterized and evaluated by High-performance Liquid Chromatography-Mass Spectrometry (HPLC-MS). Finally, preliminary microbiological tests were conducted to test the efficacy of the most promising systems as biocidal formulations both in the lab and on a model soil, and interesting results were obtained in the reduction of bacterial and fungal load, which could lead to sustainable perspectives in the field.

Enhancing Sugarcane Yield and Sugar Quality through Optimal Application of Polymer-Coated Single Super Phosphate and Irrigation Management

The judicious use of crop input is of prime importance for achieving a considerable output with a low-cost input. A two-year field experimentation was executed to assess the effect of varying polymer-coated single super phosphate (SSP) regimes on the yield and quality of sugarcane under differential water regimes. A two-factor study was executed under a randomized complete block design with a split-plot arrangement. The CPF-249 sugarcane variety was planted during the 2019-2020 period and the 2020-2021 period. The experiment consisted of four levels of polymer-coated SSP, i.e., control, 90, 110, and 130 kg ha-1, and three water regimes, which consisted of a number of irrigations, i.e., 18 irrigations, 15 irrigations, and 12 irrigations. Moreover, the water regimes were kept in the main plot, whereas the polymer-coated supplement was allocated in a subplot and replicated thrice. The data on the yield components and sugar-related traits were recorded during both years of study, and the treatment means were differentiated using an LSD test at a 95% confidence interval. Summating the findings of this study, a significant variation was revealed under the subject levels of both factors. Statistically, a 110 kg ha-1 polymer-coated SSP dose, along with 18 irrigations, declared the highest millable canes, stripped cane yield, and unstripped cane yield, followed by the 130 kg ha-1 treatment. Additionally, the highest pol% and cane sugar recovery % were recorded under 12 irrigations along with 130 kg ha-1 during both years. Similarly, the °Brix value was also significantly affected by 12 irrigations when 110 kg ha-1 of polymer-coated SSP was used. The unstripped cane yield had a strong positive correlation with the stripped cane yield, millable canes, and the number of internodes. Moreover, the commercial cane sugar % resulted in a strong positive correlation with the pol%, whereas the cane sugar recovery % revealed a strong positive correlation with the pol% and commercial cane sugar %.

Shape-recovering nanocellulose networks: Preparation, characterization and modeling

Development of strong cellulose nanofibril (CNF) networks for advanced applications, such as in the biomedical field, is of high importance owing to the biocompatible nature and plant-based origin of cellulose nanofibrils. Nevertheless, lack of mechanical strength and complex synthesis methods hinder the application of these materials in areas where both toughness and manufacturing simplicity are required. In this work, we introduce a facile method for the synthesis of a low solid content (< 2 wt%), covalently crosslinked CNF hydrogel where Poly (N-isopropylacrylamide) (NIPAM) chains are utilized as crosslinks between the nanofibrils. The resulting networks have the capability to fully recover the shape in which they were formed after various drying and rewetting cycles. Characterization of the hydrogel and its constitutive components was performed using X-ray scattering, rheological investigations and uniaxial testing in compression. Influence of covalent crosslinks was compared with networks crosslinked by the addition of CaCl₂. Among other things the results show that the mechanical properties of the hydrogels can be tuned by controlling the ionic strength of the surrounding medium. Finally, a mathematical model was developed based on the experimental results, which describes and predicts to a decent degree the large-deformation, elastoplastic behavior, and fracture of these networks.

Chitosan Hydrogels for Water Purification Applications

Chitosan-based hydrogels have gained significant attention for their potential applications in water treatment and purification due to their remarkable properties such as bioavailability, biocompatibility, biodegradability, environmental friendliness, high pollutants adsorption capacity, and water adsorption capacity. This article comprehensively reviews recent advances in chitosan-based hydrogel materials for water purification applications. The synthesis methods, structural properties, and water purification performance of chitosan-based hydrogels are critically analyzed. The incorporation of various nanomaterials into chitosan-based hydrogels, such as nanoparticles, graphene, and metal-organic frameworks, has been explored to enhance their performance. The mechanisms of water purification, including adsorption, filtration, and antimicrobial activity, are also discussed in detail. The potential of chitosan-based hydrogels for the removal of pollutants, such as heavy metals, organic contaminants, and microorganisms, from water sources is highlighted. Moreover, the challenges and future perspectives of chitosan-based hydrogels in water treatment and water purification applications are also illustrated. Overall, this article provides valuable insights into the current state of the art regarding chitosan-based hydrogels for water purification applications and highlights their potential for addressing global water pollution challenges.

Significance of biopolymer-based hydrogels and their applications in agriculture: a review in perspective of synthesis and their degree of swelling for water holding

Hydrogels are three-dimensional polymer networks that are hydrophilic and capable of retaining a large amount of water. Hydrogels also can act as vehicles for the controlled delivery of active compounds. Bio-polymers are polymers that are derived from natural sources. Hydrogels prepared from biopolymers are considered non-toxic, biocompatible, biodegradable, and cost-effective. Therefore, bio-polymeric hydrogels are being extensively synthesized and used all over the world. Hydrogels based on biopolymers finds important applications in the agricultural field where they are used as soil conditioning agents as they can increase the water retention ability of soil and can act as a carrier of nutrients and other agrochemicals. Hydrogels are also used for the controlled delivery of fertilizer to plants. In this review, bio-polymeric hydrogels based on starch, chitosan, guar gum, gelatin, lignin, and alginate polymer have been discussed in terms of their synthesis method, swelling behavior, and possible agricultural application. The urgency to address water scarcity and the need for sustainable water management in agriculture necessitate the exploration and implementation of innovative solutions. By understanding the synthesis techniques and factors influencing the swelling behavior of these hydrogels, we can unlock their full potential in fostering sustainable agriculture and mitigating the challenges posed by an ever-changing environment.

Application of polyvinyl alcohol/chitosan copolymer hydrogels in biomedicine: A review

Hydrogels is a hydrophilic, cross-linked polymer of three-dimensional network structures. The application of hydrogels prepared from a single polymer in the biomedical field has many drawbacks. The functional blend of polyvinyl alcohol and chitosan allows hydrogels to have better and more desirable properties than those produced from a single polymer, which is a good biomaterial for development and design. In this paper, we have reviewed the progress in the application of polyvinyl alcohol/chitosan composite hydrogels in various medical fields, the different cross-linking agents and cross-linking methods, and the research progress in the optimization of composite hydrogels for their subsequent wide range of biomedical applications.

Graphene oxide reinforced biopolymeric (chitosan) hydrogels for controlled cephradine release

In the current study, chitosan, poly (N-vinyl-2-pyrolidone) and polyamidoamine based hydrogels were prepared by Solution Casting Method using different quantity of graphene oxide (GO) for controlled cephradine (CPD) release. The hydrogels were characterized by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction, thermal analysis, scanning electron microscope and atomic force microscopy. FTIR results endorsed the presence of particular functionalities and developed interfaces in hydrogels. The thermal stability was directly proportional to the amount of GO. Antibacterial activity was investigated against gram-negative bacteria resultantly; CAD-2 exhibited maximum bactericidal activity against Escherichia coli and Psuedomonas aeruginosa. In addition, in-vitro biodegradation was examined in phosphate buffer saline solution and proteinase K for 21 and 07 days respectively. The maximum swelling was exhibited by CAD-133777 % in distilled water that was governed by quasi-Fickian diffusion. The swelling volumes were inversely proportional to the amount of GO. In the same way, pH sensitive CPD release was detected by UV visible spectrophotometer that followed zero order and Higuchi models. However, in 4 h, 89.4 % and 83.7 % of CPD was released in PBS and SIF solution correspondingly. Therefore, the chitosan-based biocompatible and biodegradable hydrogel platforms offered substantial potential for the controlled CPD release in medico-biological applications.

Controlled release of harmful pesticide dichlorvos through synthesized biodegradable aloe vera–acrylic acid-based hydrogel and its utilization in soil water management

The present work deals with the synthesis of biodegradable hydrogel of a natural polysaccharide aloe vera and vinyl monomer acrylic acid. In this synthesis, ammonium persulfate–glutaraldehyde was used as initiator-cross-linker system, acrylic acid as monomer and aloe vera as backbone. Grafting was confirmed by different techniques like SEM, FT-IR, XRD and EDS. Maximum percentage swelling of synthesized hydrogel was found to be 756%. Biodegradation behavior of synthesized hydrogel [Av-cl-poly(AA)] was studied by soil burial, composting and vermicomposting methods. Maximum biodegradation was found to be 90%, 94% and 93% in case of soil burial, composting and vermicomposting methods, respectively. Biodegradation of Av-cl-poly(AA) was confirmed by FT-IR and SEM techniques. Water retention capacity was prolonged from 11 to 20 days using synthesized Av-cl-poly(AA). Water content of clay soil and sandy loam soil was increased to an extent of 6.1% and 5.79%, respectively. Synthesized Av-cl-poly(AA) has been found to be effective in sustained release of harmful pesticide dichlorvos. The results showed that maximum release of dichlorvos was found to be 1024.34 ppm after 44 h.

Chitosan with Natural Additives as a Potential Food Packaging

Recently, the development of materials based on natural polymers have been observed. This is the result of increasing environmental degradation, as well as increased awareness and consumer expectations. Many industries, especially the packaging industry, face challenges resulting from legal regulations. Chitin is the most common biopolymer right after cellulose and is used to produce chitosan. Due to the properties of chitosan, such as non-toxicity, biocompatibility, as well as antimicrobial properties, chitosan-based materials are used in many industries. Many studies have been conducted to determine the suitability of chitosan materials as food packaging, and their advantages and limitations have been identified. Thanks to the possibility of modifying the chitosan matrix by using natural additives, it is possible to strengthen the antioxidant and antimicrobial activity of chitosan films, which means that, in the near future, chitosan-based materials will be a more environmentally friendly alternative to the plastic packaging used so far. The article presents literature data on the most commonly used natural additives, such as essential oils, plant extracts, or polysaccharides, and their effects on antimicrobial, antioxidant, mechanical, barrier, and optical properties. The application of chitosan as a natural biopolymer in food packaging extends the shelf-life of various food products while simultaneously reducing the use of synthetic plastics, which in turn will have a positive impact on the natural environment. However, further research on chitosan and its combinations with various materials is still needed to extent the application of chitosan in food packaging and bring its application to industrial levels.

Agricultural Applications of Superabsorbent Polymer Hydrogels

This review presents data from the past five years on the use of polymeric superabsorbent hydrogels in agriculture as water and nutrient storage and retention materials, as well as additives that improve soil properties. The use of synthetic and natural polymeric hydrogels for these purposes is considered. Although natural polymers, such as various polysaccharides, have undoubted advantages related to their biocompatibility, biodegradability, and low cost, they are inferior to synthetic polymers in terms of water absorption and water retention properties. In this regard, the most promising are semi-synthetic polymeric superabsorbents based on natural polymers modified with additives or grafted chains of synthetic polymers, which can combine the advantages of natural and synthetic polymeric hydrogels without their disadvantages. Such semi-synthetic polymers are of great interest for agricultural applications, especially in dry regions, also because they can be used to create systems for the slow release of nutrients into the soil, which are necessary to increase crop yields using environmentally friendly technologies.

Innovative bio-waste-based multilayer hydrogel fertilizers as a new solution for precision agriculture

The aim of the research work was to present a multilayer hydrogel capsule with controlled nutrient release properties as an innovative fertilizer designed for sustainable agriculture. Preparation of the capsules included the following steps: sorption of micronutrients (Cu, Mn, Zn) on eggshells (1) and their immobilization in sodium alginate, with the crosslinking agent being the NPK solution (2). The capsules were coated with an additional layer of a mixture of biopolymers (0.79% alginate, 0.24% carboxymethylcellulose and 8.07% starch)by means of dipping and spraying techniques. The biocomposites were characterized by limited (<10% within 100 h for the structures encapsulated by the dipping method) release of fertilizer ions (except for small K⁺ ions). The hydrogel fertilizer formulations were analyzed for physicochemical properties such as macro- and micronutrient content, surface morphology analysis, coating structure evaluation, mechanical properties, swelling and drying kinetics. High nutrient bioavailability was confirmed in vitro (extraction in water and neutral ammonium citrate). Germination and pot tests have revealed that the application of multicomponent hydrogel fertilizers increases the length of cucumber roots by 20%, compared to the commercial product.

Recent Advances in Smart Hydrogels Prepared by Ionizing Radiation Technology for Biomedical Applications

Materials with excellent biocompatibility and targeting can be widely used in the biomedical field. Hydrogels are an excellent biomedical material, which are similar to living tissue and cannot affect the metabolic process of living organisms. Moreover, the three-dimensional network structure of hydrogel is conducive to the storage and slow release of drugs. Compared to the traditional hydrogel preparation technologies, ionizing radiation technology has high efficiency, is green, and has environmental protection. This technology can easily adjust mechanical properties, swelling, and so on. This review provides a classification of hydrogels and different preparation methods and highlights the advantages of ionizing radiation technology in smart hydrogels used for biomedical applications.

Gel Carriers for Plant Extracts and Synthetic Pesticides in Rodent and Arthropod Pest Control: An Overview

Insecticides and rodenticides form the basis of integrated pest management systems worldwide. As pest resistance continues to increase and entire groups of chemical active ingredients are restricted or banned, manufacturers are looking for new options for more effective formulations and safer application methods for the remaining pesticide ingredients. In addition to new technological adaptations of mainstream formulations in the form of sprays, fumigants, and dusts, the use of gel formulations is becoming increasingly explored and employed. This article summarizes information on the current and potential use of gel (including hydrogel) and paste formulations against harmful arthropods or rodents in specific branches of pest management in the agricultural, food, stored product, structural wood, urban, medical, and public health areas. Due to the worldwide high interest in natural substances, part of the review was devoted to the use of gels for the formulation of pesticide substances of botanical origin, such as essential or edible oils. Gels as emerging formulation of so called “smart insecticides” based on molecular iRNA disruptors are discussed.

Controlled release fertilizers (CRFs) for climate-smart agriculture practices: a comprehensive review on release mechanism, materials, methods of preparation, and effect on environmental parameters

Fertilizers play an essential role in increasing crop yield, maintaining soil fertility, and provide a steady supply of nutrients for plant requirements. The excessive use of conventional fertilizers can cause environmental problems associated with nutrient loss through volatilization in the atmosphere, leaching to groundwater, surface run-off, and denitrification. To mitigate environmental issues and improve the longevity of fertilizer in soil, controlled release fertilizers (CRFs) have been developed. The application of CRFs can reduce the loss of nutrients, provide higher nutrient use efficiency, and improve soil health simultaneously to achieve the goals of climate-smart agricultural (CSA) practices. The major findings of this review paper are (1) CRFs can prevent direct exposure of fertilizer granule to soil and prevent loss of nutrients such as nitrate and nitrous oxide emissions; (2) CRFs are less affected by the change in environmental parameters, and that can increase longevity in soil compared to conventional fertilizers; and (3) CRFs can maintain required soil nitrogen levels, increase water retention, reduce GHG emissions, lead to optimum pH for plant growth, and increase soil organic matter content. This paper could give good insights into the ongoing development and future perspectives of CRFs for CSA practices.

Fertilizers and Fertilization Strategies Mitigating Soil Factors Constraining Efficiency of Nitrogen in Plant Production

Fertilizer Use Efficiency (FUE) is a measure of the potential of an applied fertilizer to increase its impact on the uptake and utilization of nitrogen (N) present in the soil/plant system. The productivity of N depends on the supply of those nutrients in a well-defined stage of yield formation that are decisive for its uptake and utilization. Traditionally, plant nutritional status is evaluated by using chemical methods. However, nowadays, to correct fertilizer doses, the absorption and reflection of solar radiation is used. Fertilization efficiency can be increased not only by adjusting the fertilizer dose to the plant's requirements, but also by removing all of the soil factors that constrain nutrient uptake and their transport from soil to root surface. Among them, soil compaction and pH are relatively easy to correct. The goal of new the formulas of N fertilizers is to increase the availability of N by synchronization of its release with the plant demand. The aim of non-nitrogenous fertilizers is to increase the availability of nutrients that control the effectiveness of N present in the soil/plant system. A wide range of actions is required to reduce the amount of N which can pollute ecosystems adjacent to fields.

Development of hydrogel based on Carboxymethyl cellulose/poly(4-vinylpyridine) for controlled releasing of fertilizers

A novel Carboxymethyl cellulose (CMC) and poly (4-vinylpyridine) (P4VP) hydrogel system is synthesized with different ratios, in the presence of cross-linker N, N,- methylene bis-acrylamide (MBA). The hydrogel is characterized via FTIR spectroscopy, thermal gravimetric analysis (TGA), X-ray diffraction (XRD), and scanning electron microscope (SEM). The FTIR results showed a strong interaction between both CMC, P4VP and the loaded fertilizer. The water uptake of the hydrogel was evaluated by swelling tests under variations in pH, biodegradability was investigated in soil to simulate real-world conditions. To determine the best release behavior of urea and calcium nitrate from the hydrogel, fertilizers were loaded with different ratios onto the hydrogel during its formation. Fertilizers release was followed by Atomic absorption spectroscopy to study the release of calcium nitrate and urea. Release kinetic parameters were obtained based on different mathematical models as Zero order, First order, Korsmeyer–Peppas and Higuchi models. The suitable proportionality between the mathematical models used and the fertilizers release was determined based on the correlation coefficients (R²). According to Zero order model urea release showed independent concentration. Based on Korsmeyer-Pappas and Higuchi models with high n value and R² equals to 0.97. Compared to urea, Ca²⁺, Zero order and Higuchi have been ignored due to their poor correlation coefficients values as proportion with Ca²⁺ fertilizer release.

Hydrogel Application in Urban Farming: Potentials and Limitations—A Review

Urban agriculture plays a vital role in ensuring the self-sufficiency of a great variety of fresh vegetables and nutrients. It promotes a sustainable food system as well as reducing the dependency on imports for the growing population. Urban farming has made it possible for agriculture practices to be implemented anywhere at any time in a sophisticated way. Hydrogel has been introduced in urban agriculture in the past few decades. However, the application of hydrogel in urban agriculture is still being explored in terms of hydrogel types, structure, physical and chemical properties, change due to external factors, and its suitability for different plant species. This review discusses the potentials and limitations of hydrogel in different application conditions. We present the state of knowledge on hydrogel production and crosslinking methods, hydrogel characteristics, water absorption and release mechanisms of hydrogel, hydrogel advantages and limitations, and current and future applications in urban farming.

The Characteristics of Time-Dependent Changes of Coefficient of Permeability for Superabsorbent Polymer-Soil Mixtures

Water uptake dynamics of superabsorbent polymers (SAP) in soil is of key importance for the optimum application of these materials in environmental engineering and agriculture, so goal of this paper is to determine time dependent values of coefficient of permeability for various SAP-soil mixtures. Retaining water in soil is a key requirement in critical zones to support plant growth. There is an urgent need for technologies that can increase soil water retention, given the increasing prevalence of droughts and scarcity of clean water as the climate changes, combined with the rising demand for food by a growing world population. SAPs are materials that can absorb significant amounts of water, and thus have tremendous potential to help increase water retention in soil. However, while some studies have characterized the equilibrium swelling behavior of SAPs in soil, how their addition influences the time-dependent flow of water through soil remains poorly understood. Here, we address this gap in knowledge by directly measuring the coefficient of permeability of SAP-soil mixtures, testing different soil grain sizes, SAP grain sizes, and different SAP-soil ratios. We find that SAP addition can dramatically hinder the flow rate of water through soil—reducing the permeability by several orders of magnitude, and in some cases causing complete blockage of water infiltration, at mass fractions as small as 1%. In this scenario coefficient of permeability of 1.23 × 10⁻⁴ m/s dropped by a factor of ~10 after 14 min, a factor of ~100 after 36 min, and by nearly a factor of ~1000 after 63 min, eventually causing complete blockage of infiltration after 67 min. Authors concluded that in this particular situation the size and quantity of SAP particles was enough to nearly completely fill the available pore space resulting in rendering the soil column almost completely impermeable. Moreover, we demonstrate that these effects are well-described by a simple hydraulic model of the mutual interactions between SAP and soil grains, providing more generally-applicable and quantitative principles to model SAP-soil permeability in applications. Ultimately, this work could help evaluate the optimal proportions and grain sizes of SAPs to use for a given soil to simultaneously achieve a desirable permeability along with increased water holding capacity in the plant root zone.

Recent Progress of Cellulose-Based Hydrogel Photocatalysts and Their Applications

With the development of science and technology, photocatalytic technology is of great interest. Nanosized photocatalysts are easy to agglomerate in an aqueous solution, which is unfavorable for recycling. Therefore, hydrogel-based photocatalytic composites were born. Compared with other photocatalytic carriers, hydrogels have a three-dimensional network structure, high water absorption, and a controllable shape. Meanwhile, the high permeability of these composites is an effective way to promote photocatalysis technology by inhibiting nanoparticle photo corrosion, while significantly ensuring the catalytic activity of the photocatalysts. With the growing energy crisis and limited reserves of traditional energy sources such as oil, the attention of researchers was drawn to natural polymers. Like almost all abundant natural polymer compounds in the world, cellulose has the advantages of non-toxicity, degradability, and biocompatibility. It is used as a class of reproducible crude material for the preparation of hydrogel photocatalytic composites. The network structure and high hydroxyl active sites of cellulose-based hydrogels improve the adsorption performance of catalysts and avoid nanoparticle collisions, indirectly enhancing their photocatalytic performance. In this paper, we sum up the current research progress of cellulose-based hydrogels. After briefly discussing the properties and preparation methods of cellulose and its descendant hydrogels, we explore the effects of hydrogels on photocatalytic properties. Next, the cellulose-based hydrogel photocatalytic composites are classified according to the type of catalyst, and the research progress in different fields is reviewed. Finally, the challenges they will face are summarized, and the development trends are prospected.

Study on the Incorporation of Chitosan Flakes in Electrospun Polycaprolactone Scaffolds

Hybrid scaffolds obtained by combining two or more biopolymers are studied in the context of tissue regeneration due to the possibility of achieving new functional properties or structural features. The aim of this work was to produce a new type of hybrid polycaprolactone (PCL)/chitosan (CS) electrospun mat through the controlled deposition of CS flakes interspaced between the PCL fibers. A poly(ethylene oxide) (PEO) solution was used to transport CS flakes with controlled size. This, and the PCL solution, were simultaneously electrospun onto a rotatory mandrel in a perpendicular setup. Different PCL/CS mass ratios were also studied. The morphology of the resulting fibers, evaluated by SEM, confirmed the presence of the CS flakes between the PCL fibers. The addition of PEO/CS fibers resulted in hydrophilic mats with lower Young’s modulus relatively to PCL mats. In vitro cell culture results indicated that the addition of CS lowers both the adhesion and the proliferation of human dermal fibroblasts. The present work demonstrates the feasibility of achieving a controlled deposition of a polymeric component in granular form onto a collector where electrospun nanofibers are being deposited, thereby producing a hybrid scaffold.

Hydrogels and Hydrogel Nanocomposites: Enhancing Healthcare through Human and Environmental Treatment

Humans are constantly exposed to exogenous chemicals throughout their life, which can lead to a multitude of negative health impacts. Advanced materials can play a key role in preventing or mitigating these impacts through a wide variety of applications. The tunable properties of hydrogels and hydrogel nanocomposites (e.g., swelling behavior, biocompatibility, stimuli responsiveness, functionality, etc.) have deemed them ideal platforms for removal of environmental contaminants, detoxification, and reduction of body burden from exogenous chemical exposures for prevention of disease initiation, and advanced treatment of chronic diseases, including cancer, diabetes, and cardiovascular disease. In this review, three main junctures where the use of hydrogel and hydrogel nanocomposite materials can intervene to positively impact human health are highlighted: 1) preventing exposures to environmental contaminants, 2) prophylactic treatments to prevent chronic disease initiation, and 3) treating chronic diseases after they have developed.

Novel Hydrogels for Topical Applications: An Updated Comprehensive Review Based on Source

Active pharmaceutical ingredients (API) or drugs are normally not delivered as pure chemical substances (for the prevention or the treatment of any diseases). APIs are still generally administered in prepared formulations, also known as dosage forms. Topical administration is widely used to deliver therapeutic agents locally because it is convenient and cost-effective. Since earlier civilizations, several types of topical semi-solid dosage forms have been commonly used in healthcare society to treat various skin diseases. A topical drug delivery system is designed primarily to treat local diseases by applying therapeutic agents to surface level parts of the body such as the skin, eyes, nose, and vaginal cavity. Nowadays, novel semi-solids can be used safely in pediatrics, geriatrics, and pregnant women without the possibility of causing any allergy reactions. The novel hydrogels are being used in a wide range of applications. At first, numerous hydrogel research studies were carried out by simply adding various APIs in pure form or dissolved in various solvents to the prepared hydrogel base. However, numerous research articles on novel hydrogels have been published in the last five to ten years. It is expected that novel hydrogels will be capable of controlling the APIs release pattern. Novel hydrogels are made up of novel formulations such as nanoparticles, nanoemulsions, microemulsions, liposomes, self-nano emulsifying drug delivery systems, cubosomes, and so on. This review focus on some novel formulations incorporated in the hydrogel prepared with natural and synthetic polymers.

Bacterial Alginate-Based Hydrogel Reduces Hydro-Mechanical Soil-Related Problems in Agriculture Facing Climate Change

Agricultural systems are facing the negative impacts of erosion and water scarcity, directly impacting the hydro-mechanical behavior of soil aggregation. Several technologies have been proposed to reduce hydro-mechanical soil-related problems in agriculture. Biopolymer-based hydrogels have been reported to be a great tool to tackle these problems in soils. In this study, we investigated the hydro-mechanical behavior of different soils media treated with Ca-bacterial alginate hydrogel. We used an unconfined uniaxial compression test, aggregate stability test and hydraulic conductivity measurements to investigate the mechanical and hydraulic behavior of treated soils media. Our results from unconfined uniaxial compression test showed that yield stress (i.e., strength) increased in treated soils with higher kaolinite and water content (i.e., HCM3), compared with untreated coarse quartz sand (i.e., CM1). Furthermore, we found that temperature is an important factor in the gelation capacity of our hydrogel. At room temperature, HCM3 displayed the higher aggregate stability, almost 5.5-fold compared with treated coarse quartz sand (HCM1), while this differential response was not sustained at warm temperature. In general, the addition of different quantities of kaolinite decreased the saturated hydraulic conductivity for all treatments. Finally, bright field microscopy imaging represents the soil media matrix between sand and clay particles with Ca-bacterial alginate hydrogel that modify the hydro-mechanical behavior of different soils media. The results of this study could be helpful for the soil-related problems in agriculture facing the negative effects of climate change.

Impact of Chitosan on Water Stability and Wettability of Soils

Chitosan has become increasingly applied in agriculture worldwide, thus entering the soil environment. We hypothesized that chitosan should affect the water stability of soil. Since this problem has not been studied to date, we examined, for the first time, the influence of chitosan on the water stability and wettability of soil aggregates. The aggregates were prepared from four soils with various properties amended with different amounts of two kinds of powdered chitosan, and subjected to 1 and/or 10 wetting–drying cycles. The water stability was measured by monitoring air bubbling after aggregate immersion in water, and the wettability was measured by a water drop penetration test. The biopolymer with a lower molecular mass, lower viscosity, and higher degree of deacetylation was more effective in increasing the water stability of the soil than the biopolymer with a higher molecular mass, higher viscosity, and lower deacetylation degree. After a single wetting-drying cycle, the water stability of the soil aggregates containing chitosan with a higher molecular mass was generally lower than that of the soil; after ten wetting–drying cycles, the water stability increased 1.5 to 20 times depending on the soil. The addition of low-molecular-mass chitosan after a single wetting-drying cycle caused the water stability to become one to two hundred times higher than that of the soil. A trial to find out which soil properties (pH, C and N content, bulk density, porosity, and particle size distribution) are responsible for the effectiveness of chitosan action was not successful, and this will be the objective of further studies.

Albumin Microspheres as "Trans-Ferry-Beads" for Easy Cell Passaging in Cell Culture Technology

Protein hydrogels represent ideal materials for advanced cell culture applications, including 3D-cultivation of even fastidious cells. Key properties of fully functional and, at the same time, economically successful cell culture materials are excellent biocompatibility and advanced fabrication processes allowing their easy production even on a large scale based on affordable compounds. Chemical crosslinking of bovine serum albumin (BSA) with N-(3-dimethylaminopropyl)-N’-ethylcarbodiimide hydrochloride (EDC) in a water-in-oil emulsion with isoparaffinic oil as the continuous phase and sorbitan monooleate as surfactant generates micro-meter-scale spherical particles. They allow a significant simplification of an indispensable and laborious step in traditional cell culture workflows. This cell passaging (or splitting) to fresh culture vessels/flasks conventionally requires harsh trypsinization, which can be omitted by using the “trans-ferry-beads” presented here. When added to different pre-cultivated adherent cell lines, the beads are efficiently boarded by cells as passengers and can be easily transferred afterward for the embarkment of novel flasks. After this procedure, cells are perfectly viable and show normal growth behavior. Thus, the trans-ferry-beads not only may become extremely affordable as a final product but also may generally replace trypsinization in conventional cell culture, thereby opening new routes for the establishment of optimized and resource-efficient workflows in biological and medical cell culture laboratories.

Biopolymer Hydrogel Based on Acid Whey and Cellulose Derivatives for Enhancement Water Retention Capacity of Soil and Slow Release of Fertilizers

This study describes the development of a renewable and biodegradable biopolymer-based hydrogel for application in agriculture and horticulture as a soil conditioning agent and for release of a nutrient or fertilizer. The novel product is based on a combination of cellulose derivatives (carboxymethylcellulose and hydroxyethylcellulose) cross-linked with citric acid, as tested at various concentrations, with acid whey as a medium for hydrogel synthesis in order to utilize the almost unusable by-product of the dairy industry. The water uptake of the hydrogel was evaluated by swelling tests under variations in pH, temperature and ion concentration. Its swelling capacity, water retention and biodegradability were investigated in soil to simulate real-world conditions, the latter being monitored by the production of carbon dioxide during the biodegradation process by gas chromatography. Changes in the chemical structure and morphology of the hydrogels during biodegradation were assessed using Fourier transform infrared spectroscopy and scanning electron microscopy. The ability of the hydrogel to hold and release fertilizers was studied with urea and KNO₃ as model substances. The results not only demonstrate the potential of the hydrogel to enhance the quality of soil, but also how acid whey can be employed in the development of a soil conditioning agent and nutrient release products.

Current and future perspectives on the use of nanofertilizers for sustainable agriculture: the case of phosphorus nanofertilizer

Over the last century, the demand for food resources has been continuously increasing with the rapid population growth. Therefore, it is critically important to adopt sustainable farming practices that can enhance crop production without the excessive use of fertilizers. In this regard, there is a growing interest in the use of nanomaterials for improving plant nutrition as an alternative to traditional chemical or mineral fertilizers. Using this technology, the efficiency of micro- and macro-nutrients in plants can increase. Various nanomaterials have been successfully applied in agricultural production, compared to conventional fertilizers. Among the major plant nutrients, phosphorus (P) is the least accessible since most farmlands are frequently P deficient. Hence, P use efficiency should be maximized to conserve the resource base and maintain agricultural productivity. This review summarizes the current research and the future possibilities of nanotechnology in the biofortification of plant nutrition, with a focus on P fertilizers. In addition, it covers the challenges, environmental impacts, and toxic effects that have been explored in the area of nanotechnology to improve crop production. The potential uses and benefits of nanoparticle-based fertilizers in precision and sustainable agriculture are also discussed.

Development and Characterization of Novel Cellulose Composites Obtained in 1-Ethyl-3-methylimidazolium Chloride Used as Drug Delivery Systems

Two polysaccharides (cellulose and chitosan) and polyurethane dissolved in 1-ethyl-3-methylimidazolium chloride represented the matrix for the obtainment of new composite formulations comprised of lignin, ferrite-lignin hybrid and ketoconazole. The mechanical performances (Young's modulus and compressive strength) increased with the filler addition. The nature of the filler used in the studied formulations influenced both bioadhesion and mucoadhesion parameters. It was found that the incorporation of lignin and ferrite-lignin hybrid into the matrix has influenced the in vitro rate of ketoconazole release, which is described by the Korsmeyer-Peppas model. All materials exhibited activity against Gram positive (Staphylococcus aureus ATCC 25923) and Gram negative (Escherichia coli ATCC 25922) bacteria.

Phosphates-Containing Interpenetrating Polymer Networks (IPNs) Acting as Slow Release Fertilizer Hydrogels (SRFHs) Suitable for Agricultural Applications

Novel, phosphorus-containing slow release fertilizer hydrogels (SRFHs) composed of interpenetrating polymer networks (IPNs) with very good swelling and mechanical properties have been obtained and characterized. It was found that introducing organophosphorus polymer based on a commercially available monomer, 2-methacryloyloxyethyl phosphate (MEP), as the IPN’s first component network results in much better swelling properties than for a terpolymer with acrylic acid (AAc), 2-methacryloyloxyethyl phosphate (MEP) and bis[2-(methacryloyloxy)ethyl] phosphate (BMEP) when the same weight ratios of monomers are employed. The procedure described in this paper enables the introduction of much larger amounts of phosphorus into polymer structures without significant loss of water regain ability, which is crucial in the application of such materials in the agricultural field.

A review on the applications of electrospun chitosan nanofibers for the cancer treatment

In recent years, the incidence of cancer is increasing every day due to poor quality of life (industrialization of life). Therefore, the treatment of cancer has received much attention from therapists. So far, many anticancer drugs have been used to treat cancer patents. However, the direct use of the anticancer drugs has the adverse side effects for patents and several limitations to treat process. Natural chitosan nanofibers prepared by electrospinning method have unique properties such as high surface area, high porosity, suitable mechanical properties, nontoxicity, biocompatibility, biodegradability, biorenewable, low immunogenicity, better clinical functionality, analogue to extracellular model, and easy production in large scale. Therefore, this bio-polymer is a very suitable case to deliver of the anti-cancer drugs to treat cancer patents. In this review summarizes the electrospinning synthesis of chitosan and its therapeutic application for the various cancer treatment.

Incorporation of ZnO Nanoparticles into Soy Protein-Based Bioplastics to Improve Their Functional Properties

The union of nanoscience (nanofertilization) with controlled release bioplastic systems could be a key factor for the improvement of fertilization in horticulture, avoiding excessive contamination and reducing the price of the products found in the current market. In this context, the objective of this work was to incorporate ZnO nanoparticles in soy protein-based bioplastic processed using injection moulding. Thus, the concentration of ZnO nanoparticles (0 wt%, 1.0 wt%, 2.0 wt%, 4.5 wt%) and mould temperature (70 °C, 90 °C and 110 °C) were evaluated through a mechanical (flexural and tensile properties), morphological (microstructure and nanoparticle distribution) and functional (water uptake capacity, micronutrient release and biodegradability) characterization. The results indicate that these parameters play an important role in the final characteristics of the bioplastics, being able to modify them. Ultimately, this study increases the versatility and functionality of the use of bioplastics and nanofertilization in horticulture, helping to prevent the greatest environmental impact caused.

Recent advances in the structure, synthesis, and applications of natural polymeric hydrogels

Hydrogels, polymeric network materials, are capable of swelling and holding the bulk of water in their three-dimensional structures upon swelling. In recent years, hydrogels have witnessed increased attention in food and biomedical applications. In this paper, the available literature related to the design concepts, types, functionalities, and applications of hydrogels with special emphasis on food applications was reviewed. Hydrogels from natural polymers are preferred over synthetic hydrogels. They are predominantly used in diverse food applications for example in encapsulation, drug delivery, packaging, and more recently for the fabrication of structured foods. Natural polymeric hydrogels offer immense benefits due to their extraordinary biocompatible nature. Hydrogels based on natural/edible polymers, for example, those from polysaccharides and proteins, can serve as prospective alternatives to synthetic polymer-based hydrogels. The utilization of hydrogels has so far been limited, despite their prospects to address various issues in the food industries. More research is needed to develop biomimetic hydrogels, which can imitate the biological characteristics in addition to the physicochemical properties of natural materials for different food applications.

Comparative Study of the Structural Properties, Color, Bioactive Compounds Content and Antioxidant Capacity of Aerated Gelatin Gels Enriched with Cryoconcentrated Blueberry Juice during Storage

Cryoconcentrated blueberry juice (CBJ) was incorporated into aerated gelatin gel and the effects on the mechanical properties, phenolic compounds and antioxidant activity (AA) were evaluated at day 1 and day 28 under refrigerated storage. At day 1, 8 g of gelatin gel and 40 g of CBJ (called M5) exhibited a soft texture and heterogeneous and non-spherical small bubbles, with values close to 10.5, 8.0 and 7.1 N, for hardness, gumminess and chewiness, respectively. M5 presented an increase of approximately 1.7, 1.9 and 1.9, and 1.2, 1.8, 2.1 and 1.3 times in comparison to the other samples, for total polyphenol, anthocyanin and flavonoid contents, and individual phenolic compounds, 2,2-diphenyl-1-picrylhydrazyl (DPPH), ferric reducing antioxidant power (FRAP) and oxygen radical absorbance capacity (ORAC) assays, respectively. At day 28, the samples showed a weakening of the 3D network, with high degradation of phenolic compounds and AA due to the oxidation, polymerization and syneresis. Therefore, CBJ might be an interesting functional ingredient to add to (aerated and non-aerated) gelatin gel without affecting its properties, and thus different food products with high nutritional values and without added artificial sweeteners could be developed. Additionally, the gelatin gel/CBJ combinations might be suitable for additive manufacturing as a coating of food matrices.